Thermal reactor with improved gas flow distribution

ABSTRACT

Embodiments of the present invention provide apparatus and method for improving gas distribution during thermal processing. One embodiment of the present invention provides an apparatus for processing a substrate comprising a chamber body defining a processing volume, a substrate support disposed in the processing volume, wherein the substrate support is configured to support and rotate the substrate, a gas inlet assembly coupled to an inlet of the chamber body and configured to provide a first gas flow to the processing volume, and an exhaust assembly coupled to an outlet of the chamber body, wherein the gas inlet assembly and the exhaust assembly are disposed on opposite sides of the chamber body, and the exhaust assembly defines an exhaust volume configured to extend the processing volume.

CROSS-REFERENCE TO RELATED APPLICATION

This Patent Application is a continuation application of co-pending U.S.patent application Ser. No. 12/339,671 filed Dec. 19, 2008, which claimspriority to U.S. Provisional Patent Application Ser. No. 61/015,435filed Dec. 20, 2007 (Attorney Docket No. APPM/11945L). Each of theaforementioned patent applications is incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a semiconductor processingtool and, more specifically, to a thermal reactor with improved gas flowdistribution.

2. Description of the Related Art

Rapid thermal processing, commonly referred to as ‘RTP’, subjects asubstrate to a very brief, intense burst of heat that can go from roomtemperature to about 1000° C. in seconds. RTP technology is used tochange the characteristics of a deposited film or crystal lattice. RTPgenerally includes processes such as annealing, silicidation andoxidation of a substrate surface.

Generally, an RTP chamber includes a radiant heat source or lamp, achamber body, a substrate support ring, and a process gas supplyingsystem. The radiant heat source is typically mounted on a top surface ofthe chamber body so that the energy generated by the heat sourceradiates upon the substrate supported by the substrate support ringwithin the chamber body. A quartz window is typically disposed in thetop surface of the chamber body to facilitate energy transferring fromthe heat source to the substrate. An external motor is usually used torotate the support ring and the substrate to compensate for variationsin the radiation energy generated by the lamp that could heat thesubstrate non-uniformly. A rapid thermal process may be performed at areduced pressure to get better uniformity.

Processing gases, for example oxygen source in an oxidation process, areusually supplied to the chamber from a gas inlet, and are kept flowingin the chamber by a pumping system connected to chamber. Gasdistribution in a conventional chamber is not uniform across thechamber. For example, gas distribution near the gas inlet is differentfrom gas distribution near the pumping port, and gas distribution nearthe edge region is different from gas distribution near the centerregion. Although, continuous rotation of the substrate may reduce thenon-uniformity of gas distribution, the rotation alone may not be enoughas the requirement for uniformity increases.

Therefore, there is a need for a thermal reactor with improved gas flowdistribution.

SUMMARY OF THE INVENTION

The present invention provides methods and apparatus for performing athermal process. More particularly, embodiments of the present inventionprovide apparatus and method for improving gas distribution duringthermal processing.

One embodiment of the present invention provides an apparatus forprocessing a substrate comprising a chamber body defining a processingvolume, a substrate support disposed in the processing volume, whereinthe substrate support is configured to support and rotate the substrate,a gas inlet assembly coupled to an inlet of the chamber body andconfigured to provide a first gas flow to the processing volume, and anexhaust assembly coupled to an outlet of the chamber body, wherein thegas inlet assembly and the exhaust assembly are disposed on oppositesides of the chamber body, and the exhaust assembly defines an exhaustvolume configured to extend the processing volume.

Another embodiment of the present invention provides an apparatus forthermal processing a substrate comprising a base ring having sidewallsdefining a cylindrical center volume, wherein the base ring has an inletport and an outlet port formed through the sidewalls, the inlet port andthe outlet port are formed on opposite sides, and each of the inlet portand the outlet port has a width that approximates a diameter of thecylindrical center volume, a top wall coupled to the base ring to sealthe cylindrical center volume from an upper end of the sidewalls, a heatsource disposed above the top wall and configured to provide thermalenergy to the cylindrical center volume, a bottom wall coupled to thebase ring to seal the cylindrical center volume from a lower end of thesidewalls, a substrate support disposed in the cylindrical centervolume, wherein the substrate support is configured to support androtate the substrate, an injection cartridge coupled to the base ring inthe inlet port, wherein the injection cartridge is configured to providea first gas flow to the cylindrical center volume, and an exhaustassembly coupled to the outlet port of the base ring, wherein theexhaust assembly is configured to pull the first gas flow from the inletport to the outlet port.

Yet another embodiment of the present invention provides a method forprocessing a substrate comprising providing a process chamber defining aprocessing volume, wherein the process chamber has an inlet port and anexhaust port formed on opposite sides of the process chamber, and widthsof the inlet port and outlet port approximate a diameter of thesubstrate, positioning the substrate in a processing volume, providing afirst gas flow from the inlet port to the outlet port, wherein the firstgas flow are directed from a plurality of injection holes evenlydistributed along the width of the inlet port, and pumping theprocessing volume using an exhaust assembly coupled to the outlet port,wherein the exhaust assembly defines an exhaust volume that extends theprocessing volume along the direction of the first gas flow.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic sectional side view of a thermal reactor inaccordance with one embodiment of the present invention.

FIG. 2 is a schematic sectional top view of a thermal reactor having agas distribution system in accordance with one embodiment of the presentinvention.

FIG. 3 is a schematic sectional top view of a thermal reactor having agas distribution system in accordance with another embodiment of thepresent invention.

FIG. 4 is a schematic exploded view of a base ring of a thermal reactorin accordance with one embodiment of the present invention.

FIG. 5 is a schematic sectional side view of an injection cartridge inaccordance with one embodiment of the present invention.

FIG. 6 is a schematic perspective sectional view of an exhaust assemblyin accordance with one embodiment of the present invention.

FIG. 7 is a schematic perspective sectional view of a side injectionassembly in accordance with one embodiment of the present invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

The present invention provides methods and apparatus for thermallyprocessing semiconductor substrates. Thermal processing chambers of thepresent invention comprise an exhaust assembly configured to extend aprocessing volume along a direction of a gas flow to improve gasdistribution uniformity. Embodiments of the present invention furthercomprise a side injection assembly configured to provide a side flow toimprove edge processing. Additionally, thermal processing chambers ofthe present invention comprise an injection cartridge having two or moreinput to improve flow uniformity across a length of an injection port.

FIG. 1 is a schematic sectional side view of a thermal processingchamber 200 in accordance with one embodiment of the present invention.

The thermal processing chamber 200 generally comprises a lamp assembly210, a chamber assembly 230 defining a processing volume 239, and asubstrate support 238 disposed in the processing volume 239.

The lamp assembly 210 is positioned above the chamber assembly 230 andis configured to supply heat to the processing volume 239 via a quartzwindow 214 disposed on the chamber assembly 230. The lamp assembly 210is configured to house a heating source, such as a plurality oftungsten-halogen lamps for providing a tailored infrared heating meansto a substrate 201 disposed on the substrate support 238.

The lamp assembly 210 generally comprises a plurality of light pipes211. The light pipes 211 may be made of stainless steel, brass, aluminumor other metal. Each of the light pipes 211 is configured to house aradiant energy source 208, for example a tungsten-halogen lamp toprovide heat to the processing volume 239 in form of infrared radiation.The ends of the light pipes 211 are brazed or welded to openings in anupper cooling wall 216 and a lower cooling wall 217.

In one embodiment, the light pipes 211 may be disposed in a hexagonalarrangement. Coolant may be circulated to the lamp assembly 210 throughan inlet 209 to keep the lamp assembly 210 cool during processing. Eachof the radiant energy source 208 may be connected to a controller 207which may control the energy level of each radiant energy source 208 toachieve a uniform or tailored heating profile to the processing volume239.

The chamber assembly 230 generally comprises a base ring 240 definingthe processing volume 239 with the quartz window 214 and a bottom wall(not shown).

The base ring 240 may have an inlet 231 adapted to a gas source 235configured to provide one or more processing gases to the processingvolume 239. An outlet 234, formed on an opposite side of the base ring240 from the inlet 231, is adapted to an exhaust assembly 224 which isin fluid communication with a pump system 236. The exhaust assembly 224defines an exhaust volume 225, which is in fluid communication with theprocessing volume 239 via the outlet 234. The exhaust volume 225 isdesigned to allow uniform gas flow distribution across the processingvolume 239.

A silt valve 237 may be adapted to the inlet 231 of the base ring 240for a robot to drop/retrieve the substrate 201 on/from a substratesupport 238 positioned in the processing volume 239. The substratesupport 238 may be configured to move vertically and to rotate about acentral axis 223.

In one embodiment, the base ring 240 may have one or more side ports 222formed on sides of the base ring 240 between the inlet 231 and theoutlet 234. The side openings 222 may be connected to a side gas sourceconfigured to improve gas distribution uniformity near edge areas of thesubstrate 201.

FIG. 2 is a schematic sectional top view of the thermal processingchamber 200 showing a gas distribution system in accordance with oneembodiment of the present invention.

As shown in FIG. 2, the inlet 231 and outlet 234 are formed through thebase ring 240 on opposite sides of the processing volume 239. Both ofthe inlet 231 and the outlet 234 have a width which approximates adiameter of the substrate support 238.

In one embodiment, the gas source 235 may comprise multiple gas sources,for example a first gas source 241, and a second gas source 242, eachconfigured to provide a processing gas. Processing gases from the firstgas source 241 and the second gas source 242 may mix together prior toentering an injection cartridge 249 disposed in the inlet 231.

In one embodiment, the injection cartridge 249 has an elongated channel250 formed therein and two inlets 243, 244 formed on opposite ends ofthe elongated channel 250. A plurality of injecting holes 251 are evenlydistributed along the elongated channel 250 and are configured to injecta gas flow 245 towards the processing volume 239. The two-inlet designof the cartridge 249 improves uniformity among the gas flow from each ofthe plurality of injecting holes 251.

Under the vacuum force from the pump system 236, the gas flow 245 isdirected from the inlet 231 towards the outlet 234. It is desirable tohave the gas flow 245 uniform across the processing volume 239 from theinlet 231 to the outlet 234. In one embodiment, the exhaust volume 225of the exhaust assembly 224 is configured to extend the processingvolume 239 to reduce the geometry influence of the chamber structure tothe gas flow 245. Particularly, the exhaust volume 225 is configured toextend the processing volume 239 along the direction of the gas flow245.

In one embodiment, a side injection assembly 247 is coupled to the basering 240 so that a side gas flow 248 is provided to the processingvolume 239 via the side port 222. The side injection assembly 247 iscoupled to the gas source 235 via a flow adjusting device 246 configuredto control a flow rate of the side gas flow 248. The side port 222 isgenerally formed through the base ring 240 between the inlet 231 and theoutlet 234.

The side gas flow 248 is configured to adjust edge profile of thesubstrate 201 being processed. In one embodiment, the side gas flow 248increases gas exposure of the substrate 201 near the edge area. In oneembodiment, the side gas flow 248 may be directed at a directionsubstantially perpendicular to the gas flow 245. In one embodiment, theeffect of the side gas flow 248 on the edge may be adjusted by adjustinga flow rate of the side gas flow 248.

As discussed above, the substrate 201 typically rotates about its centerduring process. The substrate 201 may be rotated along either counterclockwise or clockwise direction. The rotation of the substrate 201 maydrag the side gas flow 248 away from the outlet 234 so that the side gasflow 248 may have increased effect on the substrate 201.

In one embodiment, the side gas flow 248 may come from the mixed gassource and comprise the same gas components as the gas flow 245, asshown in FIG. 2. In another embodiment, the side gas flow 248 maycomprise only part of the gas components in the gas flow 245, orcomprise different gas components from the gas flow 245. FIG. 3 is aschematic sectional top view of the thermal processing chamber 200having a gas distribution system which provides only one processing gascomponent through the side gas flow 248.

Even though, FIGS. 2-3 show the substrate 201 is rotating along counterclockwise direction, the substrate 201 may be rotated along clockwisedirection and also benefit from the side gas flow 248.

FIG. 4 is a schematic exploded view of a base ring assembly 300 forproviding a uniform gas flow in accordance with one embodiment of thepresent invention.

The base ring assembly 300 comprises a base ring 301 defining acylindrical processing volume 314 configured to process a substratetherein. The base ring 301 has an inlet port 310 and an outlet port 311formed at opposite sides of the cylindrical processing volume 314. Inone embodiment, widths of the inlet port 310 and the outlet port 311 aresubstantially similar to a diameter of the cylindrical processing volume314 to assure uniform gas flow from the inlet port 310 to the outletport 311.

The base ring assembly 300 further comprises an injection cartridge 304connected with the inlet port 310. The injection cartridge 304 isconfigured to provide a gas flow from the inlet port 310 to the outletport 311. A notch 315 is formed on the base ring 301 above the inputport 310 and an elongated throw hole 316 is formed on a bottom of thenotch 315 and open to the input port 310. The cartridge 304 isconfigured to provide processing gases through the elongated throw hole316 to the input port 310 and the cylindrical processing volume 314.During processing, the input port 310 is typically used to allow passageof substrates being processed.

FIG. 5 is a schematic sectional side view of the injection cartridge 304in accordance with one embodiment of the present invention. Theinjection cartridge 304 has an elongated body 347 with a flange 341. Theflange 341 allows the injection cartridge 304 to be inserted into theelongated through hole 316. A lid 346 is coupled to the elongated body347 to seal the elongated channel 342.

The elongated body 347 has an elongated channel 342 formed therein.Inlets 343, 344 are formed through both ends of the elongated body 347to the elongated channel 342. The inlets 343, 344 are configured toconnect with a gas source. A plurality of ports 345 are formed on abottom of the elongated body 347 to connect the elongated channel 342with outside volume.

During processing, a process gas comes from both of the inlets 343, 344,fills up the elongated channel 342 and exits the injection cartridge 304from the plurality of ports 345 to the input port 310 of the base ring301.

An exhaust assembly 302 is coupled to the base ring 301 near the outletport 311. The exhaust assembly 302 has an opening 321 substantiallysimilar to the outlet port 311 providing extra volume to allow uniformgas flow in the cylindrical processing volume 314.

FIG. 6 is a schematic perspective sectional view of the exhaust assembly302 in accordance with one embodiment of the present invention. Theexhaust assembly 302 comprises a flange 325 configured to connect to thebase ring 301, a body 326 defining an exhaust volume 322, and an exhaust323 configured to connect with a pumping system. A plurality of coolingchannels 324 are formed in the exhaust assembly 302 and configured tocontrol temperature of the exhaust assembly 302 using cooling or heatingfluid.

The exhaust volume 322 of the exhaust assembly 302 is configured toextend the cylindrical processing volume 314 of the base ring 301 alongthe direction from the inlet port 310 to the outlet port 314. In oneembodiment, the exhaust volume 322 may have a tapered shape with onewide end connecting to the opening 321 and one narrow end connecting tothe exhaust 323. The tapered shape allows gradual gathering of a gasflow spread across the width of the opening 321 to narrow entrance ofthe exhaust 323, thus minimizing turbulence to the gas flow in thecylindrical processing volume 314. A triangle shaped exhaust volume 322is illustrated in FIGS. 4 and 6, however, any shape that reducesturbulence to the gas flow is contemplated.

The base ring assembly 300 further comprises one or two side injectionassemblies 303 coupled to side ports 313 or 312 formed on through thebase ring 301. The side ports 312, 313 are formed between the inlet port310 and the outlet port 311 and are configured to allow a side gas flowto the cylindrical processing volume 314. As previously discussed, theside gas flow is configured to tune edge processing profile.

FIG. 7 is a schematic perspective sectional view of the side injectionassembly 303 in accordance with one embodiment of the present invention.The side injection assembly 303 comprises a face plate 331 configured toconnect with the base ring 301, a body 332 defining a gas chamber 335, adiffuser plate 333 sandwiched between the body 332 and the face plate331, and an inlet 336 configured to connect the gas chamber 335 with agas source. The diffuser plate 333 has a plurality of through holes 334configured to provide a gas flow from the gas chamber 335 to thecylindrical processing volume 314 of the base ring 301. In oneembodiment, the diffuser plate 333 may be formed from ceramic.

Even though a thermal processing chamber is discussed in thisapplication, embodiments of the present invention may be used in anyprocessing chamber where uniform gas flow is desired.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. An apparatus for processing a substrate,comprising: sidewalls defining a center volume, wherein an inlet portand an outlet port are formed through the sidewalls on opposite sides ofthe center volume; a top wall coupled to an upper end of the sidewalls;a bottom wall coupled a lower end of the sidewalls; a substrate supportdisposed in the center volume; an injection assembly coupled to thesidewalls at the inlet port; and an exhaust assembly coupled to thesidewalls at the outlet port, wherein exhaust assembly comprises a bodydefining an exhaust volume, an exhaust port is formed through the bodyfor connection with a pump system, the exhaust volume connects to thecenter volume through the outlet port, and the exhaust volume extends adistance between the inlet port and the exhaust port along the directionfrom the inlet port to the outlet port.
 2. The apparatus of claim 1,wherein both the inlet port and outlet port have a width approximate awidth of the substrate support.
 3. The apparatus of claim 2, wherein theexhaust volume has a tapered shape having a wide end and a narrow end,the outlet port is coupled to the wide end, and the exhaust port ispositioned at the narrow end.
 4. The apparatus of claim 2, wherein theinjection assembly comprises a cartridge disposed in the inlet port, thecartridge has two input ports configured to connect with a gas source,and a plurality of injection ports evenly distributed across a width ofthe cartridge.
 5. The apparatus of claim 2, wherein the center volume iscylindrical, the substrate support is circular, and the inlet port andthe outlet port have a width approximate a diameter of the substratesupport.
 6. The apparatus of claim 5, further comprising a first sideinjection assembly coupled to a first side port formed through thesidewalls, wherein the first side port is formed between the inlet portand the outlet port.
 7. The apparatus of claim 6, further comprising aflow adjusting device connected to the first side injection assembly. 8.The apparatus of claim 6, further comprising a second side injectionassembly coupled to a second side port formed through the sidewalls,wherein the first and second side ports are formed on opposite sides ofthe sidewalls.
 9. The apparatus of claim 6, wherein the side injectionassembly comprises a baffle plate having a plurality of injection holesconfigured to directing a process gas towards the center volume.
 10. Theapparatus of claim 1, further comprising: a quartz window; and a heatingassembly is outside the quartz window and configured to provide thermalenergy to the cylindrical center volume.
 11. The apparatus of claim 10,wherein the quartz window is disposed in an opening of the top wall, andthe heating assembly is disposed above the top wall.
 12. The apparatusof claim 11, wherein the heating assembly comprises a plurality of lampsdisposed in a hexagonal arrangement.
 13. The apparatus of claim 10,wherein the body of the exhaust assembly includes cooling channels. 14.A method for processing a substrate, comprising: providing a processchamber defining a processing volume, wherein the process chamber has aninlet port and an exhaust port formed on opposite sides of the processchamber, and widths of the inlet port and outlet port approximate adiameter of the substrate; positioning the substrate in a processingvolume; providing a first gas flow from the inlet port to the outletport, wherein the first gas flow are directed from a plurality ofinjection holes evenly distributed along the width of the inlet port;and pumping the processing volume using an exhaust assembly coupled tothe outlet port, wherein the exhaust assembly defines an exhaust volumethat extends the processing volume along the direction of the first gasflow.
 15. The method of claim 14, further comprising providing a secondgas flow from a side port of the process chamber to the processingvolume, wherein the direction of the second gas flow is substantiallyperpendicular to the direction of the first gas flow.
 16. The method ofclaim 15, further comprising rotating the substrate continuously about acenter of the substrate.
 17. The method of claim 16, wherein rotatingthe substrate comprises rotating the substrate along a direction so thata velocity of an edge of the substrate near the side port issubstantially opposite to the direction of the first gas flow.
 18. Themethod of claim 14, wherein the first gas flow are provided by an inletcartridge disposed in the inlet port, the inlet cartridge has anelongated flow channel, the elongated flow channel is connected to twoinput ports formed on opposite ends of the elongated flow channel and aplurality of output holes evenly distributed along the elongated flowchannel.
 19. The method of claim 14, wherein the exhaust volume has atapered shape with a wide end coupled to the outlet and a narrow endcoupled to a vacuum pump.
 20. The method of claim 14, further comprisingheating the substrate using a heat source disposed above the processingvolume.